ATI RN
Genetic Disorders in Pediatrics Questions
Question 1 of 5
The most common cystic fibrosis mutation consists of:
Correct Answer: A
Rationale: The most common CF mutation is ΔF508, a 3-base-pair deletion in CFTR.
Question 2 of 5
A full-term female newborn is examined shortly after birth. She appears to be small for gestational age, and she has excess skin on the nape of the neck and lymphedema of the hands and feet. Chromosomal analysis shows some cells with a normal 46,XY karyotype and some cells with a 45,X karyotype. Which of the following mechanisms best explains this cytogenetic abnormality?
Correct Answer: A
Rationale: Mosaicism (46,XY/45,X) arises from mitotic nondisjunction post-fertilization, losing an X or Y in some cells.
Question 3 of 5
In the following partial sequence of mRNA, a mutation of the template DNA results in a change in codon 91 to UAA. What type of mutation is it? | 88 | 89 | 90 | 91 | 92 | 93 | 94 | GUC | GAC | CAG | UAG | GGC | UAA | CCG |
Correct Answer: C
Rationale: UAG is a stop codon; changing codon 91 to UAA (another stop) is nonsense, causing premature termination.
Question 4 of 5
Which of the following fetal tissues are used for studying the fetal chromosomes:
Correct Answer: C
Rationale: Amniotic fluid (C) is used in amniocentesis to study fetal chromosomes. Rationale: It contains fetal cells (e.g., amniocytes) that can be cultured for karyotyping, unlike lymphocytes (postnatal) or cheek swabs (not fetal). Skin biopsy and bone marrow are less common prenatally.
Question 5 of 5
The most commonly used stain for metaphase chromosomes is?
Correct Answer: B
Rationale: Giemsa stain (B) is standard for G-banding in karyotyping. Rationale: Giemsa produces dark (G-positive) and light bands, widely used for chromosome identification. Quinacrine (Q-banding) and trypsin (pre-treatment) are less common alone.